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The human factor in licensing and operating the next generation of nuclear plants
As human factors specialists working at the intersection of human performance and nuclear operations, we are witnessing one of the nuclear sector’s most significant transitions in decades. The emergence of small modular reactors, microreactors, and other advanced designs is reshaping the industry’s landscape. Digital instrumentation and controls, passive safety systems, and increased automation are creating opportunities for greater safety margins and more flexible operation. These same features also fundamentally redefine what it means to “operate” a nuclear plant. Interactions among human roles, automation, and passive systems shape how people maintain awareness, exercise judgment, and intervene when necessary. These developments affect both operational realities and the regulatory foundations on which nuclear safety is built.
Joseph O. Erb, James G. Miller
Nuclear Technology | Volume 83 | Number 3 | December 1988 | Pages 367-373
Technical Paper | Fifth International Retran Meeting / Heat Transfer and Fluid Flow | doi.org/10.13182/NT88-A34149
Articles are hosted by Taylor and Francis Online.
The rod ejection transient is a postulated Condition IV event initiated by the mechanical failure of a control rod mechanism pressure housing. Such a failure results in the rapid ejection of a rod cluster control assembly from the core, followed by a fast reactivity insertion. A severe asymmetric core power distribution may result, possibly leading to fuel rod damage. Reactor protection for the transient is provided by negative reactivity feedback effects and by reactor trips on high neutron flux levels. This transient has been modeled for Virginia Electric and Power Company’s Surry and North Anna nuclear power stations using RETRAN-02. The analysis is performed in two parts. First, the core average power history is calculated using a single-loop model with point kinetics and three axially stacked core control volumes. The ejected rod’s reactivity is inserted linearly over 0.1 s. The negative reactivity feedback effects due to Doppler and moderator temperature changes and the reactor trip are also modeled. The effect of the locally peaked core flux shape, omitted by the nominal point kinetics model, is approximated by applying a conservative power weighting factor to the Doppler reactivity feedback. The core average power history is adjusted to represent peak core power conditions and input to the hot spot thermal-hydraulic analysis model. The hot spot model, which represents a single fuel rod at the core’s peak power, predicts maximum fuel enthalpy and temperature transients. This model has two control volumes, one for the hot spot location and the second for a sink for flow from the hot channel. From these results, the amount of fuel damage and the radiological consequences can be assessed.